Classmates can compete directly against each other with the KELVIN® Tug-of War Activity or they can compete indirectly with the KELVIN® Tractor Pull. By altering gear ratios, vehicle weight, traction systems and wheel sizes student's build vehicles with the greatest pulling power. They can try to move the greatest weight or pull another vehicle across the threshold. A fun learning experience.

Requires variable power supply for operation (see left column). Can be used with a single KELVIN® Power Supply (#841386, 841051 or 841052) controlling both vehicles simultaneously. Two KELVIN® Power Supplies can be used with one powering each vehicle, or a KELVIN® Dual Power Supply (#841387) can be used to power both vehicles. Note: You must enlarge holes for gears.